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The analogy between the phenomena of water-spouts, and electricity, may be made visible by hanging a drop of water to a wire, communicating with the prime conductor, and placing a vessel of water under it. In these circumstances, the drop assumes all the various appearances of a water-spout, in its rise, form, and mode of disappearing
Water-spouts, at sea, are undoubtedly very like whirlwinds and hurricanes by Land. These sometimes tear up trees, throw down buildings, make caverns; and, in all the cases, they scatter the earth, bricks, stones, timber, &c. to a great distance in every direction. Dr. Franklin, mentions a remarkable appearance which occurred to Mr. Wilke, a consdierable electrician.. On the 20th of July, 1758, at three o'clock in the afternoon, he observed a great quantity of dust rising from the ground, and covering a field, and part of the town in which he then was. There was no wind, and the dust moved gently lightning strikes the earth in two opposite places.
James. I wonder the discharge does not shake the earth, as the charge of a jar does any thing through which it passes.
Tutor. Every discharge of clouds through the earth may do this, though it is imperceptible to us.
Earthquakes are probably occasioned by vast discharges of the electric fluid: they happen most frequently in dry and hot countries, which are subject to lightning, and other electric phenomena : they are even foretold by the electric coruscations, and other appearances in the air for some days preceding the event. Besides, the shock of an earthquake is instantaneous to the greatest distances. Earthquakes are usually accompanied with rain, and sometimes by the most dreadful thunderstorms:
How greatly terrrible how dark and deep
White age and youth, the guilty and the just,
TUTOR. If you stand on the stool with glass legs, and hold the chain from the conductor while I work the machine a few minutes, your pulse will be increased, that is, it will beat more frequently than it did before. From this circumstances physicians have applied electricity to the cure of many disorders : in some of which their endeavours have been unavailing, in others the success has been very complete.
Charles. Did they do nothing more than this?
Tutor. Yes, in some cases they took sparks from their patients, in others they gave them shocks.
James. This would be no pleasant method of cure, if the shocks were strong.
Tutor. You know, by means of Lane's electrometer, described in our thirty fourth Conversation, (Plate vir. Fig. 10.) the shock may be given as slightly as you please.
Charles. But how are shocks conveyed through any part of the body?
Tutor. There are machines and apparatus made purposely for medical purposes, but every end may be answered by the instrument just referred to. Suppose the electrometer to be fixed to a Leyden phial, and the knob at a to touch the conductor, and the knob B to be so far off as you mean the shocks to be weak or strong, a chain or wire of sufficient length is to be fixed to the ring c of the electrometer, and another wire or chain to the outside coating: the other ends of these two wires are to be fastened to the two knobs of the discharging-rod. VOL. III.